Limits...
Epicatechin gallate, a naturally occurring polyphenol, alters the course of infection with β-lactam-resistant Staphylococcus aureus in the zebrafish embryo.

Stevens CS, Rosado H, Harvey RJ, Taylor PW - Front Microbiol (2015)

Bottom Line: No significant increases in survival were noted when infected embryos were maintained in medium containing 12.5-100 μg/mL ECg with or without 4 or 16 μg/mL oxacillin.However, when EMRSA-16 was grown in medium containing 12.5 μg/mL ECg and the bacteria used to infect embryos by either the circulation valley or yolk sac, there were significant increases in embryo survival in both the presence and absence of oxacillin.We conclude that exposure to ECg prior to infection reduces the lethality of EMRSA-16, renders cells more susceptible to elimination by immune processes and compromises their capacity to establish an inflammatory response in comparison to non-exposed bacteria.

View Article: PubMed Central - PubMed

Affiliation: UCL School of Pharmacy, University College London London, UK.

ABSTRACT
(-)-epicatechin gallate (ECg) substantially modifies the properties of Staphylococcus aureus and reversibly abrogates β-lactam resistance in methicillin/oxacillin resistant (MRSA) isolates. We have determined the capacity of ECg to alter the course of infection in zebrafish embryos challenged with epidemic clinical isolate EMRSA-16. At 30 h post fertilization (hpf), embryos were infected by injection of 1-5 × 10(3) colony forming units (CFU) of EMRSA-16 into the circulation valley or yolk sac. Infection by yolk sac injection was lethal with a challenge dose above 3 × 10(3) CFU, with no survivors at 70 hpf. In contrast, survival at 70 hpf after injection into the circulation was 83 and 44% following challenge with 3 × 10(3) and 1-5 × 10(3) CFU, respectively. No significant increases in survival were noted when infected embryos were maintained in medium containing 12.5-100 μg/mL ECg with or without 4 or 16 μg/mL oxacillin. However, when EMRSA-16 was grown in medium containing 12.5 μg/mL ECg and the bacteria used to infect embryos by either the circulation valley or yolk sac, there were significant increases in embryo survival in both the presence and absence of oxacillin. ECg-modified and unmodified, GFP-transformed EMRSA-16 bacteria were visualized within phagocytic cells in the circulation and yolk sac; pre-treatment with ECg also significantly increased induction of the respiratory burst and suppressed increases in IL-1β expression typical of infection with untreated EMRSA-16. We conclude that exposure to ECg prior to infection reduces the lethality of EMRSA-16, renders cells more susceptible to elimination by immune processes and compromises their capacity to establish an inflammatory response in comparison to non-exposed bacteria.

No MeSH data available.


Related in: MedlinePlus

Induction of the respiratory burst in 30 hpf zebrafish embryos following infection by the circulation valley with 1 × 104 CFU EMRSA-16, 1 × 104 CFU ECg-grown EMRSA-16 or PBS sham-injection control. Embryos were induced with 400 ng/mL of phorbol myristate acetate in the presence of 1 μg/mL H2DCFDA and the intensity of the fluorescent signal measured as indicated. n = 10 per group; ∗P < 0.05; log rank test.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4585009&req=5

Figure 5: Induction of the respiratory burst in 30 hpf zebrafish embryos following infection by the circulation valley with 1 × 104 CFU EMRSA-16, 1 × 104 CFU ECg-grown EMRSA-16 or PBS sham-injection control. Embryos were induced with 400 ng/mL of phorbol myristate acetate in the presence of 1 μg/mL H2DCFDA and the intensity of the fluorescent signal measured as indicated. n = 10 per group; ∗P < 0.05; log rank test.

Mentions: Uptake of injected EMRSA-16 by phagocytes suggests that the embryos mount a partially successful primary innate immune response to the challenge. We therefore determined the capacity of embryos to produce reactive oxygen species by measurement of the NADPH oxidase-dependent respiratory burst following injection of EMRSA-16 or ECg-grown EMRSA-16 into the circulation valley (Figure 5). At 1 hpi the response of embryos infected with ECg-grown EMRSA-16 was significantly higher compared to PBS-injected embryos; in contrast, there was no significant difference between controls and embryos infected with untreated EMRSA-16. At 26 hpi, embryos infected with untreated and ECg-grown bacteria displayed a significant response, although the respiratory burst associated with untreated EMRSA-16 was weaker than that found with embryos infected with ECg-exposed EMRSA-16. Sham-injection also induced a relatively large response but this was not significantly different from the untreated control. These associations were less pronounced at 40 hpi and were not evident at 50 hpi. These data suggest that ECg-grown bacteria were more readily countermanded by the innate defenses of the embryo, reflecting attenuated virulence following exposure to ECg. However, there were only small, insignificant changes in the distribution of the GFP label following uptake of EMRSA-16-GFP and the ECg-grown equivalent. Figure 6 shows the distribution of label associated with 10,000 blood cells at 17 hpi of embryos infected at 30 hpf with ECg-grown and untreated bacteria.


Epicatechin gallate, a naturally occurring polyphenol, alters the course of infection with β-lactam-resistant Staphylococcus aureus in the zebrafish embryo.

Stevens CS, Rosado H, Harvey RJ, Taylor PW - Front Microbiol (2015)

Induction of the respiratory burst in 30 hpf zebrafish embryos following infection by the circulation valley with 1 × 104 CFU EMRSA-16, 1 × 104 CFU ECg-grown EMRSA-16 or PBS sham-injection control. Embryos were induced with 400 ng/mL of phorbol myristate acetate in the presence of 1 μg/mL H2DCFDA and the intensity of the fluorescent signal measured as indicated. n = 10 per group; ∗P < 0.05; log rank test.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585009&req=5

Figure 5: Induction of the respiratory burst in 30 hpf zebrafish embryos following infection by the circulation valley with 1 × 104 CFU EMRSA-16, 1 × 104 CFU ECg-grown EMRSA-16 or PBS sham-injection control. Embryos were induced with 400 ng/mL of phorbol myristate acetate in the presence of 1 μg/mL H2DCFDA and the intensity of the fluorescent signal measured as indicated. n = 10 per group; ∗P < 0.05; log rank test.
Mentions: Uptake of injected EMRSA-16 by phagocytes suggests that the embryos mount a partially successful primary innate immune response to the challenge. We therefore determined the capacity of embryos to produce reactive oxygen species by measurement of the NADPH oxidase-dependent respiratory burst following injection of EMRSA-16 or ECg-grown EMRSA-16 into the circulation valley (Figure 5). At 1 hpi the response of embryos infected with ECg-grown EMRSA-16 was significantly higher compared to PBS-injected embryos; in contrast, there was no significant difference between controls and embryos infected with untreated EMRSA-16. At 26 hpi, embryos infected with untreated and ECg-grown bacteria displayed a significant response, although the respiratory burst associated with untreated EMRSA-16 was weaker than that found with embryos infected with ECg-exposed EMRSA-16. Sham-injection also induced a relatively large response but this was not significantly different from the untreated control. These associations were less pronounced at 40 hpi and were not evident at 50 hpi. These data suggest that ECg-grown bacteria were more readily countermanded by the innate defenses of the embryo, reflecting attenuated virulence following exposure to ECg. However, there were only small, insignificant changes in the distribution of the GFP label following uptake of EMRSA-16-GFP and the ECg-grown equivalent. Figure 6 shows the distribution of label associated with 10,000 blood cells at 17 hpi of embryos infected at 30 hpf with ECg-grown and untreated bacteria.

Bottom Line: No significant increases in survival were noted when infected embryos were maintained in medium containing 12.5-100 μg/mL ECg with or without 4 or 16 μg/mL oxacillin.However, when EMRSA-16 was grown in medium containing 12.5 μg/mL ECg and the bacteria used to infect embryos by either the circulation valley or yolk sac, there were significant increases in embryo survival in both the presence and absence of oxacillin.We conclude that exposure to ECg prior to infection reduces the lethality of EMRSA-16, renders cells more susceptible to elimination by immune processes and compromises their capacity to establish an inflammatory response in comparison to non-exposed bacteria.

View Article: PubMed Central - PubMed

Affiliation: UCL School of Pharmacy, University College London London, UK.

ABSTRACT
(-)-epicatechin gallate (ECg) substantially modifies the properties of Staphylococcus aureus and reversibly abrogates β-lactam resistance in methicillin/oxacillin resistant (MRSA) isolates. We have determined the capacity of ECg to alter the course of infection in zebrafish embryos challenged with epidemic clinical isolate EMRSA-16. At 30 h post fertilization (hpf), embryos were infected by injection of 1-5 × 10(3) colony forming units (CFU) of EMRSA-16 into the circulation valley or yolk sac. Infection by yolk sac injection was lethal with a challenge dose above 3 × 10(3) CFU, with no survivors at 70 hpf. In contrast, survival at 70 hpf after injection into the circulation was 83 and 44% following challenge with 3 × 10(3) and 1-5 × 10(3) CFU, respectively. No significant increases in survival were noted when infected embryos were maintained in medium containing 12.5-100 μg/mL ECg with or without 4 or 16 μg/mL oxacillin. However, when EMRSA-16 was grown in medium containing 12.5 μg/mL ECg and the bacteria used to infect embryos by either the circulation valley or yolk sac, there were significant increases in embryo survival in both the presence and absence of oxacillin. ECg-modified and unmodified, GFP-transformed EMRSA-16 bacteria were visualized within phagocytic cells in the circulation and yolk sac; pre-treatment with ECg also significantly increased induction of the respiratory burst and suppressed increases in IL-1β expression typical of infection with untreated EMRSA-16. We conclude that exposure to ECg prior to infection reduces the lethality of EMRSA-16, renders cells more susceptible to elimination by immune processes and compromises their capacity to establish an inflammatory response in comparison to non-exposed bacteria.

No MeSH data available.


Related in: MedlinePlus